As shown in FIG. 5, a high-frequency switch having two input terminals and two output terminals is used to switch two antenna terminals (hereinafter referred to simply as “terminals”) 111 and 112 to transmitting terminal (terminal) 113 and receiving terminal (terminal) 114. In other words, in state 1 shown by solid line arrows, terminals 111 and 113, and terminals 112 and 114 are connected respectively. Alternatively, in state 2 shown by broken line arrows, terminals 112 and 113, and terminals 111 and 114 are connected respectively. Known are high-frequency switches using so-called compound semiconductors, such as GaAs, or those using p-intrinsic-n (PIN) diodes. As shown in FIG. 6, a PIN diode passes current when voltage in the forward direction is applied thereto, and does not pass current when voltage in the reverse direction is applied thereto. Such a high-frequency switch is disclosed in the Japanese Patent Unexamined Publication No. H07-74672, for example.
FIG. 7 shows a layout diagram of electronic components in a conventional high-frequency switch. PIN diodes 121, 122, 123, and 124, inductors 131, 132, 133, and 134, by-pass capacitors 141, 142, 143, and 144, and resistors 151, 152, 153, and 154 are disposed on the surface layer of circuit board (board) 170.
In a case that a high-frequency switch is structured of PIN diodes, the PIN diodes are connected as shown in FIG. 8. If this configuration is applied to the arrangement of FIG. 7, terminals 111 and 112 on the input side and terminals 113 and 114 on the output side are not disposed in the opposite configuration of FIG. 5. For this reason, the high-frequency switch is extremely user-unfriendly. To solve this problem, pattern wirings are routed on the inner layer of board 170 as shown in FIG. 9. In other words, by routing from terminal 111 to electrode 111A, terminal 112 to electrode 112A, terminal 113 to electrode 113A, and terminal 114 to electrode 114A, the terminals are interchanged. Thus, terminals 111 and 112 on the input side and terminals 113 and 114 on the output side are connected to input and output terminals of PIN diodes 121, 122, 123, and 124.
However, interchanging the terminals in this manner increases the length of the wiring patterns and a transmission loss, thus making impedance matching difficult.